Low cost and scalable manufacture of lab-on-chip devices for applications such as point-of-care testing is an urgent need. Weaving is presented as a unified, scalable and low-cost platform for the manufacture of fabric chips that can be used to perform such testing. Silk yarns with different properties are first selected, treated with the appropriate reagent solutions, dried and handloom-woven in one step into an integrated fabric chip. This platform has the unique advantage of scaling up production using existing and low cost physical infrastructure. We have demonstrated the ability to create pre-defined flow paths in fabric by using wetting and non-wetting silk yarns and a Jacquard attachment in the loom. Further, we show that yarn parameters such as the yarn twist frequency and weaving coverage area may be conveniently used to tune both the wicking rate and the absorptive capacity of the fabric. Yarns optimized for their final function were used to create an integrated fabric chip containing reagent-coated yarns. Strips of this fabric were then used to perform a proof-of-concept immunoassay with sample flow taking place by capillary action and detection being performed by a visual readout.

We present textile weaving as a new technique for the manufacture of miniature electrochemical sensors with significant advantages over current fabrication techniques. Biocompatible silk yarn is used as the material for fabrication instead of plastics and ceramics used in commercial sensors. Silk yarns are coated with conducting inks and reagents before being handloom-woven as electrodes into patches of fabric to create arrays of sensors, which are then laminated, cut and packaged into individual sensors. Unlike the conventionally used screen-printing, which results in wastage of reagents, yarn coating uses only as much reagent and ink as required. Hydrophilic and hydrophobic yarns are used for patterning so that sample flow is restricted to a small area of the sensor. This simple fluidic control is achieved with readily available materials. We have fabricated and validated individual sensors for glucose and hemoglobin and a multiplexed sensor, which can detect both analytes. Chronoamperometry and differential pulse voltammetry (DPV) were used to detect glucose and hemoglobin, respectively. Industrial quantities of these sensors can be fabricated at distributed locations in the developing world using existing skills and manufacturing facilities. We believe such sensors could find applications in the emerging area of wearable sensors for chemical testing.

There is a rising need for low-cost and scalable platforms for sensitive medical diagnostic testing. Fabric weaving is a mature, scalable manufacturing technology and can be used as a platform to manufacture microfluidic diagnostic tests with controlled, tunable flow. Given its scalability, low manufacturing cost (<$0.25 per device), and potential for patterning multiplexed channel geometries, fabric is a viable platform for the development of analytical devices. In this paper, we describe a fabric-based electrophoretic platform for protein separation. Appropriate yarns were selected for each region of the device and weaved into straight channel electrophoretic chips in a single step. A wide dynamic range of analyte molecules ranging from small molecule dyes (<1 kDa) to macromolecule proteins (67-150 kDa) were separated in the device. Individual yarns behave as a chromatographic medium for electrophoresis. We therefore explored the effect of yarn and fabric parameters on separation resolution. Separation speed and resolution were enhanced by increasing the number of yarns per unit area of fabric and decreasing yarn hydrophilicity. However, for protein analytes that often require hydrophilic, passivated surfaces, these effects need to be properly tuned to achieve well-resolved separations. A fabric device tuned for protein separations was built and demonstrated. As an analytical output parameter for this device, the electrophoretic mobility of a sedimentation marker, Naphthol Blue Black bovine albumin in glycine-NaOH buffer, pH 8.58 was estimated and found to be -2.7 × 10(-8) m(2) V(-1) s(-1). The ability to tune separation may be used to predefine regions in the fabric for successive preconcentrations and separations. The device may then be applied for the multiplexed detection of low abundance proteins from complex biological samples such as serum and cell lysate.

The demand for methods and technologies capable of rapid, inexpensive and continuous monitoring of health status or exposure to environmental pollutants persists. In this work, the development of novel surface-enhanced Raman spectroscopy (SERS) substrates from metal-coated silk fabric, known as zari, presents the potential for SERS substrates to be incorporated into clothing and other textiles for the routine monitoring of important analytes, such as disease biomarkers or environmental pollutants. Characterization of the zari fabric was completed using scanning electron microscopy, energy dispersive X-ray analysis and Raman spectroscopy. Silver nanoparticles (AgNPs) were prepared, characterized by transmission electron microscopy and UV-vis spectroscopy, and used to treat fabric samples by incubation, drop-coating and in situ synthesis. The quality of the treated fabric was evaluated by collecting the SERS signal of 4,4'-bipyridine on these substrates. When AgNPs were drop-coated on the fabric, sensitive and reproducible substrates were obtained. Adenine was selected as a second probe molecule, because it dominates the SERS signal of DNA, which is an important class of disease biomarker, particularly for pathogens such as Plasmodium spp. and Mycobacterium tuberculosis. Excellent signal enhancement could be achieved on these affordable substrates, suggesting that the developed fabric chips have the potential for expanding the use of SERS as a diagnostic and environmental monitoring tool for application in wearable sensor technologies.

[a] 1IntroductionContinuous monitoring of health remotely using wearable sensors and body area networks [ 1] is receiving al ot of attention both in the academiaa sw ell as industry. The challenges in the area of networking are well studied and addressed. Wearable sensor technology,o nt he other hand, is enticingf or researchers,a si to ffers several challenges that need to be addressed. These include developing of wearable sensors which are flexible,d urable, reliable,b iocompatible and robust. Havings ensor output as an electrical signal is of great additional value as it aids in seamless integration of well-developed, alliede lectronics wherein transduction and wireless transmission could be carried out simultaneously,t hus enabling smart and remote healthcare.Need for minimally invasive and continuous real-time monitoring of physiologicala ctivities has ushered in aw ave of wearable sensors. Starting from the commercially successfulm inimally invasiveg lucose watch, aw ide range of wearable sensors were developedo ver the past decade for continuous monitoring of vital physiological parameters of clinical importance. At extileb ased device integrated with an electronic board for continuous remote monitoring of heartr ate and respirationr ate is demonstrated [2].T he field of wearable electrocardiogram (ECG) and electroencephalogram (EEG) electrodes has receivedawide attention with severalE CG bands and EEG headset systemsi ntegrated with wireless sensor networks successfully demonstrated [3][4][5][6][7][8].T he key challenge that is being addressed in the sensor side is the development of dry electrodes which are devoid of any gel [9][10][11][12].S pecifically in the case of ECG bands,i ti s nearly impossible to createa1 2l ead wearable electrode system which is comfortable owing to the locationso ft he electrodes.T he wearable sensors for ECG typically have three leads and it is essential to convert this three lead ECG signalt otraditional twelve lead ECG signal for the sakeo fd octors who are trained to diagnoset he patient conditionb asedo nt welve lead data. Al ot of signal processing algorithms and electronic boards are being developed for this purpose [13,14].Ac omprehensive review on wearable sensors for humanp hysiological monitoring is published and wellc ited in the literature [ 15].T he aforementioned sensors are traditionally non-invasive as they sense electrical signals and there is no analyte involved in the same.Sports and fitness regimesh ave seen as ubstantial increase in the deployment of non-invasive wearable sensors. Unlike ECG and EEG electrodes,t hese sensors predominantly detect analytesi ns weat. Aw earables ensor comprising humidity sensors embedded in textile was usedt om onitors weat rate [16].L ikewise,e lectrolytes in sweat that are of clinical importancew ere detected utilising multiwalledc arbon nanotubes embedded in nylon cloth [17].Electrochemical transduction is the ideal mechanism for developingw earable sensors for remotem onitoringa s the output of these devices beinge ...